Abstract
Purpose:
To report the dissociation between ganglion cell analysis (GCA)/ ganglion cell complex (GCC) measurements and peripapillary retinal nerve fiber layer (RNFL) measurements on SD-OCT in patients with hereditary retinal disease
Methods:
A retrospective study was performed on 47 patients with symmetric hereditary retinal disease who had SD-OCT macular scans and peripapillary RNFL thickness scans. Five patients had Achromatopsia, two patients had Leber Congenital Amaurosis, 35 patients had non-syndromic Retinitis Pigmentosa, two patients had Usher’s Syndrome, and one patient had X-Linked Juvenile Retinoschisis. Macular and RNFL scans were performed on the Cirrus SD-OCT or I-Vue SD-OCT. The macular scans were used to determine the GCA on the Cirrus SD-OCT and the GCC on the I-Vue. GCA/GCC thickness and peripapillary RNFL thickness values were classified as supernormal, normal or abnormal, based on comparison with the instruments’ normative database.
Results:
For the total group (all conditions), 78.72% of eyes demonstrated abnormal GCA/GCC thickness. 31.91% of the eyes with abnormal GCA/GCC thickness demonstrated supernormal RNFL thickness and 46.81% of eyes demonstrated normal RNFL thickness. The results for the 35 patients with Retinitis Pigmentosa revealed that 85.71% of eyes had abnormal GCA/GCC thickness. 34.29% of these eyes had supernormal RNFL thickness and 51.43% had normal RNFL thickness.
Conclusions:
In hereditary retinal degenerations, there appears to be a dissociation between the GCA/GCC thickness, which was abnormal and peripapillary RNFL thickness, which was either supernormal or normal in the vast majority of patients. This has implications for the use of GCA/GCC analyses, popular in the diagnosis of glaucoma, but which must be used with caution in patients with hereditary retinal degenerations who may also be glaucoma suspects. One explanation is that the two technologies do not measure the same populations: the peripapillary (RNFL) measurements reflect 100% of the axons whereas the ganglion cell measurements only reflect a reported 50% of the total ganglion cell population. The ganglion cells which are measured by the GCC/GCA correlate higher with the temporal peripapillary measurement. In addition, an algorithm failure of inner retinal measurements in patients with outer retinal pathology cannot be ruled out.
Keywords: 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) •
696 retinal degenerations: hereditary